The present disclosure relates generally to energy absorbers for use in a vehicle, and especially to lower-leg protection devices.
A challenge for design engineers in the automotive market is pedestrian safety, e.g., controlling the knee bending. Traditionally and the most commonly used solution with respect to lower-leg protection is the metal spoilers (e.g., tubes) or a leg-spoiler which extends below bumper beam (e.g., U.S. Pat. No. 6,513,843 B1 to Frederick et al. for a Pedestrian Protection Leg Spoiler). These solutions, although very simple, can be heavy and therefore are not usually preferred by the automobiles original equipment manufacturers (OEMs). Other inherent disadvantages of these metal spoilers include non-uniform stiffness across the vehicle width, limitations in the geometry and shape of the component, insufficient deformation in the impact direction, and relatively higher stiffness than desired. These disadvantages add to the difficulty of using metal for such a solution. Moreover, use of a separate cover over the bottom portion of the vehicle to protect from rocks, dirt, and the like, cannot be avoided if metal spoilers are used.
A second solution comprises a simple plastic sheet/tray (undertray). Although this solution prevents stone and other components from chipping the inside of the vehicle engine compartment, it requires very high or often impossible mold thickness to achieve the required amount of stiffness. Therefore, the tray is a heavy, inefficient, and not a cost effective solution for lower-leg protection.
A third solution relates to complex, injection molded designs that use a lower bumper stiffener. These are again not observed to be very efficient, lightweight and cost effective solutions because of their complex geometric configurations and high thickness and mass. In addition to the issues of weight and mass, a further disadvantage of all of these solutions is that they move very little in the impact direction.
Hence, there is a need for a lower-leg device having a reduced weight compared to current solutions, and being capable of moving in the impact direction.